Great progress has been made in cotton resistance to Verticillium wilt.

Verticillium dahliae is a destructive plant pathogenic fungus, which has a wide range of hosts and can infect more than 400 kinds of plants, including many crops of important economic value. Verticillium wilt caused by Verticillium dahliae costs more than billions of dollars a year worldwide. Cotton Verticillium wilt caused by Verticillium dahliae is the most serious fungal disease in cotton growing areas in the world, which not only significantly reduces cotton yield but also greatly reduces fiber quality. Generally, the yield will be reduced by 10% to 30%. The yield of serious cotton fields can be reduced by more than 80%, or even no harvest.

Verticillium dahliae was introduced into China when it was introduced from the United States in 1935, and then spread rapidly. At present, about half of the cotton planting areas in China are affected by Verticillium dahliae, which has become the most serious disease in cotton production. The economic loss is up to 15 ~ 2 billion yuan per year, and the loss is huge.

Verticillium dahliae is a soil-borne pathogen, which forms microsclerotia in soil to resist adverse environment for more than 10 years, and there is no effective fungicide in production so far. therefore, the cultivation of disease-resistant cotton varieties is considered to be an important means to control Verticillium wilt. However, due to the lack of effective resistance sources, high resistance varieties have not been successfully cultivated so far. Therefore, Verticillium wilt has always been regarded as the "cancer" of cotton.

Gastrodia elata is a kind of traditional Chinese medicine, which has been used for more than 1000 years in China. It was found that the existence of a small molecular weight antifungal protein in the epidermis and cortical parenchyma cells of Gastrodia elata tubers is the basis of this defense system. In vitro antifungal activity experiments show that gafps has a very broad spectrum of antibacterial activity and has a strong inhibitory effect on many plant pathogenic fungi, indicating that it has a great application prospect in plant antifungal genetic engineering.

Wang Yiqin, associate researcher of Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, cloned an antifungal protein gene named gafp from Gastrodia elata by protein purification, sequencing and cdna library screening. It was proved that gafp had good resistance to many fungi including Verticillium wilt. Further screening of Gastrodia genomic library showed that there were four gafp genes in Gastrodia elata. Through the comparative study of the activities of the four members, it was found that a new member gafp4 had the strongest antibacterial activity in vivo and in vitro, and the signal peptide with interstitial localization could significantly enhance the resistance. Through more than 10 years cooperation with Li Fuguang Research Group of Cotton Institute of Chinese Academy of Agricultural Sciences, Jian Guiliang Research Group of Plant Protection Institute of Chinese Academy of Agricultural Sciences and Jiao Gaili Research Group of Cotton Institute of Shanxi Academy of Agricultural Sciences, gafp4 was transferred to two upland cotton cultivars, and Verticillium wilt identification experiments were carried out in Yuncheng, Henan and Langfang, Hebei for three consecutive years. Gafp4 has obvious resistance to different physiological types of Verticillium dahliae and is an effective protein with high resistance to cotton Verticillium wilt. What is particularly important is that the fiber yield of gafp4 transgenic cotton has also increased by 20.7% to 51.7%. Therefore, this research result makes it possible to overcome the "incurable disease" of cotton by means of plant genetic engineering.